Disclosed is a surface heat-treatment method using an electronic beam, and the method for heat-treating a surface by emitting an electronic beam at the surface of a basic material made of carbon steel, which is ferrite, at room temperature comprises: a processing region setting step of setting a local processing region on the surface of the basic material; and an output control step of controlling an output of an electronic beam emitted at a processing region, wherein the output control step controls the output of the electronic beam according to the heat conductivity of the basic material such that a part of the basic material, which has been melted by the electronic beam within the processing region and deviated from the processing region according to the movement of the electronic beam, can be transformed into stable austenite at room temperature by being rapidly coagulated by heat conduction due to a relative mass difference with the entire basic material. In addition, disclosed is a surface heat-treatmen
